1. Field of the Invention
The invention relates and pertains to tapping attachments, i.e. tools which carry taps for threading holes and are driven by a driving machine or power center, and to methods for disassembling and reassembling tapping attachments.
2. Description of the Prior Art
The field of the invention and the prior art are exemplified in the field of self-reversing tapping attachments by reference to prior patents assigned to the assignee of the instant application. These include: U.S. Pat. Nos. 3,999,642; 4,014,421; 4,566,829; 4,705,437; 5,203,651; 5,209,616; and 5,213,413 and patents cited therein, all of which are hereby incorporated by reference herein. The aforesaid patents disclose and claim tapping attachments including a tap holding spindle and simultaneously rotating forward and reverse drivers, the spindle being freely floating and moveable axially with respect to the forward and reverse drivers. Under forward drive in which the tap holder spindle is driven by the forward driver, the tap threads a hole being tapped in the workpiece and thereby screws itself into the hole. Upon cessation of feed by the driving machine with retraction of the driving machine, relative axial movement results between the tap holding spindle and the driver members such that the forward drive member becomes disengaged from the tap spindle which at this point is held relatively stationary due to the fact that the tap has become fastened to the workpiece. Upon further retractive movement by the tapping machine and further relative movement, the reverse drive member becomes engaged with the tap holding spindle, causing reverse rotation thereof and thereby unscrewing the tap from the hole. In this manner, self-reversing by the tapping attachment itself as opposed to reversing by the driving machine, is accomplished. With the advent of powerful Computer Numeric Control (CNC) machining centers, self-reversing has become of greater and greater importance in that it causes reversing to occur in the tapping attachment, as opposed to requiring the driving machine to reverse its direction of rotation.
Self-reversing tapping attachments as exemplified in the above-cited patents among others, have particular parts which due to the very nature of self-reversing suffer greater wear than other parts. These parts include elements of the drivers. Replacement of worn parts in existing tapping attachments produces delays and down time. Disassembly of existing tapping attachments in itself requires appreciable time and some degree of skill.
In addition, the delays and downtime introduced by disassembling existing tapping attachments have been accompanied by a pattern of usage thereof such that the tapping attachments are used until they basically break down. At that time, they are either discarded or taken out of service for repair and maintenance. Tools for accomplishing disassembly tend to be small and easily misplaced or lost, thus introducing further delays and downtime regarding repair and maintenance.
Further, in existing tapping attachments force, and stress tend to be transmitted to the driving machine and worn parts do not perform as well in terms of reversing and initiating tapping as well as performance thereof.
Additionally, in existing tapping attachments, replacement of worn drivers normally involves replacement of both forward and reverse drivers when such replacement occurs on the occasion of breakdown due to wear.
All of the forgoing aspects of operation of existing tapping attachments tend to diminish efficiency and increase costs and downtime.
Therefore, there has been a felt but unfulfilled need for a tapping attachment which is readily disassembleable for inspection and maintenance with tools which are handy and tend not to be misplaced, which concentrates stress in a minimum number of parts, whose parts are readily replaceable and rearrangeable to continue to perform service in the tapping attachment.